default or selected kernelversion does not have config value CONFIG_BT_HCIUART_BCSP_TXCRC.
Result is shown for kernelversion 5.4.123

Transmit CRC with every BCSP packet

configname: CONFIG_BT_HCIUART_BCSP_TXCRC

Linux Kernel Configuration
└─>Networking support
└─>Bluetooth subsystem support
└─>Bluetooth device drivers
└─>Transmit CRC with every BCSP packet
In linux kernel since version 2.6.12  
If you say Y here, a 16-bit CRC checksum will be transmitted along with
every BCSP (BlueCore Serial Protocol) packet sent to the Bluetooth chip.
This increases reliability, but slightly reduces efficiency.